Why would someone pretend to be a cancer patient who became pregnant after being raped by her uncle?

Although Munchausen Syndrome — a condition in which patients fake illness to get attention, often undergoing unnecessary tests and surgeries — is rare, such online versions of such fraud are becoming common enough to concern people with real life-threatening illnesses in virtual support groups. And as psychiatrists debate which disorders will be included in the next edition of their manual, the Diagnostic and Statistical Manual of Mental Disorders (DSM), the role of digital influences remains an understudied but emerging segment of mental illnesses. The next DSM is due to be released in its fifth version in May 2013.

Seattle’s weekly The Stranger published a compelling feature on one such case, in which a woman suffering from cancer is first befriended then stalked online by not one, but two fraudulent patients. Valerie, a 36-year-old Washington woman, endured an emotional nightmare as she sought support in fighting a highly aggressive form of breast cancer.

Valerie began to blog about her battle with cancer. She wanted to keep her family abreast of her treatment and, hopefully, find support from someone going through the same physical and emotional struggle she was. She named her Tumblr blog CatsNotCancer because she loves cats (not cancer).

Over the course of the next year, Valerie would bluntly document her daily ups and downs: How she named her breasts and the cancerous lymph node she would ultimately have chopped off; her ceremonious Viking boob funeral, where she lit boob-shaped candles and set them adrift in Lake Washington as guests snacked on boob-adorned cupcakes; the shaving of her beautiful red hair for Locks of Love (“I couldn’t bear to watch it fall out”).

Unfortunately, aside from attracting a genuinely supportive readership, the blog also drew in a woman named Beth, who claimed she had lymphoma and then that she became pregnant by being raped by her uncle during the time she was undergoing chemotherapy. In the article, Madrid describes how Beth and, incredibly, another cancer faker, used pseudonyms and invented stories so byzantine that those who fell for them later found it hard to understand how they had done so.

Experts say that what they now call “Munchausen by Internet” affects primarily the same groups of people at risk for Munchausen Syndrome itself: mainly women, starting in their late teens or early 20s, often with personality disorders and typically those who work in a medical field like nursing. They estimate that 1% to 5% of hospital patients have faked or significantly exaggerated their illnesses; some claim the disease costs the medical system billions of dollars.

Writes Madrid:

The lies slowly escalate, pile up, and create an improbable whole. Then one day, you realize you’re friends with a 15-year-old chronic migraine sufferer online who also happens to be a fourth-year medical school student who plays drums in a band at night—despite those crippling migraines—to pay his med school tuition because his deaf mother and alcoholic stepfather have no interest in his baby-genius education. Oh, and since he’s not yet old enough to drive, he skateboards three miles a day to get to class.

And on that day, you feel like a total schmuck.

She describes how Valerie eventually unraveled Beth’s deceit and then was befriended by yet another internet cancer poseur — and also interviews both of the women who perpetrated the frauds. One, distressingly, is now writing a blog about motherhood.

In the draft version of the DSM-5, Munchausen Syndrome will be retained, but as of yet, there’s no official diagnosis for the online version, which, although rare, is clearly more common than the real-world type, given its prevalence in online support groups. In 2010, four consecutive cases made headlines.

While experts have debated whether internet addiction constitutes a diagnosable disorder, Munchausen’s by Internet has not been discussed as extensively. (Internet addiction is placed in the category for “future study” in the upcoming DSM-5.) At issue are questions such as whether Munchausen by internet is an extreme form of internet trolling, or another example of how the feeling of anonymity we get from being online can disinhibit people and exacerbate antisocial tendencies. Only by studying and debating questions like these can potential sufferers, and their victims, be protected from the consequences of perpetrating a fictitious illness online.